On Mon, May 12, 2025 at 12:04 PM Jonathan Wakely <[email protected]> wrote:
> This was a regression introduced with using version.def to define
> feature test macros.
Could you add link to commit here, I think this
is r14-3248-g083b7f2833d71d.
> std::scoped_lock can be defined unconditionally
> (including for freestanding).
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/120198
> * include/bits/version.def (scoped_lock): Do not depend on
> gthreads or hosted.
> * include/bits/version.h: Regenerate.
> * include/std/mutex (scoped_lock): Update comment.
> * testsuite/30_threads/scoped_lock/requirements/typedefs.cc:
> Remove dg-require-gthreads and use custom lockable type instead
> of std::mutex. Check that typedef is only present for a single
> template argument.
> ---
>
> Tested x86_64-linux.
>
LGTM.
>
> libstdc++-v3/include/bits/version.def | 2 --
> libstdc++-v3/include/bits/version.h | 2 +-
> libstdc++-v3/include/std/mutex | 2 +-
> .../scoped_lock/requirements/typedefs.cc | 28 ++++++++++++++++---
> 4 files changed, 26 insertions(+), 8 deletions(-)
>
> diff --git a/libstdc++-v3/include/bits/version.def
> b/libstdc++-v3/include/bits/version.def
> index f4d3de88bb2b..2d34a8dff7fc 100644
> --- a/libstdc++-v3/include/bits/version.def
> +++ b/libstdc++-v3/include/bits/version.def
> @@ -679,8 +679,6 @@ ftms = {
> values = {
> v = 201703;
> cxxmin = 17;
> - hosted = yes;
> - gthread = yes;
> };
> };
>
> diff --git a/libstdc++-v3/include/bits/version.h
> b/libstdc++-v3/include/bits/version.h
> index d5d75cef2de1..24831f70b417 100644
> --- a/libstdc++-v3/include/bits/version.h
> +++ b/libstdc++-v3/include/bits/version.h
> @@ -751,7 +751,7 @@
> #undef __glibcxx_want_parallel_algorithm
>
> #if !defined(__cpp_lib_scoped_lock)
> -# if (__cplusplus >= 201703L) && defined(_GLIBCXX_HAS_GTHREADS) &&
> _GLIBCXX_HOSTED
> +# if (__cplusplus >= 201703L)
> # define __glibcxx_scoped_lock 201703L
> # if defined(__glibcxx_want_all) || defined(__glibcxx_want_scoped_lock)
> # define __cpp_lib_scoped_lock 201703L
> diff --git a/libstdc++-v3/include/std/mutex
> b/libstdc++-v3/include/std/mutex
> index b3f89c0b9435..e575a81c138e 100644
> --- a/libstdc++-v3/include/std/mutex
> +++ b/libstdc++-v3/include/std/mutex
> @@ -733,7 +733,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> }
>
> -#ifdef __cpp_lib_scoped_lock // C++ >= 17 && hosted && gthread
> +#ifdef __cpp_lib_scoped_lock // C++ >= 17
> /** @brief A scoped lock type for multiple lockable objects.
> *
> * A scoped_lock controls mutex ownership within a scope, releasing
> diff --git
> a/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
> b/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
> index 4cd07da44657..ba52b36a3111 100644
> ---
> a/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
> +++
> b/libstdc++-v3/testsuite/30_threads/scoped_lock/requirements/typedefs.cc
> @@ -1,5 +1,4 @@
> // { dg-do compile { target c++17 } }
> -// { dg-require-gthreads "" }
> // { dg-add-options no_pch }
>
> // Copyright (C) 2017-2025 Free Software Foundation, Inc.
> @@ -29,9 +28,30 @@
> # error "Feature-test macro for scoped_lock has wrong value"
> #endif
>
> +struct BasicLockable
> +{
> + BasicLockable() = default;
> + ~BasicLockable() = default;
> + void lock() { }
> + void unlock() { }
> +};
> +
> void test01()
> {
> - // Check for required typedefs
> - typedef std::scoped_lock<std::mutex> test_type;
> - typedef test_type::mutex_type mutex_type;
> + // Check for required typedef.
> + using test_type = std::scoped_lock<BasicLockable>;
> + static_assert(std::is_same_v<test_type::mutex_type, BasicLockable>);
> +}
> +
> +template<typename T, typename = void>
> +constexpr bool has_mutex_type = false;
> +
> +template<typename T>
> +constexpr bool has_mutex_type<T, std::void_t<typename T::mutex_type>> =
> true;
> +
> +void test02()
> +{
> + // Check that typedef is absent as required.
> + using test_type = std::scoped_lock<BasicLockable, BasicLockable>;
> + static_assert(!has_mutex_type<test_type>);
> }
> --
> 2.49.0
>
>
